CN107257784B

CN107257784B - For extracting C from aqueous streams1To C4Quaternary carboxylate compositions of carboxylic acids

Info

Publication number: CN107257784B
Application number: CN201580076522.2A
Authority: CN
Inventors: R.T.亨布雷; S.D.巴尼基; C.W.辛克; C.哈达克雷; J.刘; F.齐
Original assignee: Eastman Chemical Co
Current assignee: Eastman Chemical Co
Priority date: 2014-12-19
Filing date: 2015-12-18
Publication date: 2021-07-06
Anticipated expiration: 2035-12-18
Also published as: EP3233871B1; US9616358B2; US9573078B2; WO2016100769A1; EP3233872B1; US20160175738A1; EP3233871A1; CN107250094B; EP3233872A1; CN107257784A; US20160175737A1; WO2016100768A1; CN107250094A

Abstract

The invention relates to a method for extracting C from an aqueous stream₁To C₄A solvent for the carboxylic acid. More specifically, the extraction solvent comprises one or more salts comprised of tetraalkylphosphonium cations and carboxylate anions. The extraction solvent may further comprise one or more non-ionic liquid organic solvents as an enhancer. The extraction solvent can be used to extract an aqueous mixture containing one or more lower carboxylic acids, such as monocarboxylic acids, alkoxycarboxylic acids, and halogen-containing carboxylic acids.

Description

For extracting C from aqueous streams1To C4Quaternary carboxylate compositions of carboxylic acids

Cross reference to related applications

The present application claims the benefit of provisional application No. 62/094,238 filed 2014 12, 19, § 119(e) (1); the entire contents of this provisional application are incorporated herein by reference.

Technical Field

The present invention generally relates to methods for extracting C from aqueous streams₁To C₄Solvents for carboxylic acids, compositions containing them and methods for separating acids from water.

Background

Recovery of C from aqueous streams₁To C₄Carboxylic acids (hereinafter "lower acids") are common industrial problems arising from various reactions and processing steps. Simple distillation of wet acid stream to recover glacial acid suffers from unfavorable vapor-liquid equilibrium (VLE) and all C₁To C₄The high energy cost of carboxylic acids hinders. Examples of adverse VLEs include formic acid-water highest boiling point homogeneous azeotropes, acetic acid-water VLE "pinches" (regions of low relative volatility), and water and all C₃-C₄The lowest boiling point homogeneous azeotrope of carboxylic acid.

Various methods have been proposed in the art to address the problem of recovering lower acids from wet acid feeds. For example, one method subjects an aqueous solution of a lower acid to azeotropic distillation with an entraining component that forms a heterogeneous minimum boiling azeotrope with water such that the azeotrope boils at a temperature significantly lower than pure water, pure lower acid, and any acid-water azeotrope. The extraction step is usually preceded by azeotropic distillation. The extraction step partitions the carboxylic acid into a water immiscible solvent (which is typically the same as the azeotropic entrainer) to remove most of the water from the recovered acid. Have been in the artNumerous examples of azeotropic distillation, extraction, and combinations thereof using conventional organic solvents are presented. These include U.S. patent nos. 1,839,894; 1,860,512, respectively; 1,861,841, respectively; 1,917,391, respectively; 2,028,800, respectively; 2,050,234, respectively; 2,063,940, respectively; 2,076,184, respectively; 2,123,348, respectively; 2,157,143, respectively; 2,184,563, respectively; 2,199,983, respectively; 2,204,616, respectively; 2,269,163, respectively; 2,275,834, respectively; 2,275,862, respectively; 2,275,867, respectively; 2,317,758, respectively; 2,333,756, respectively; 2,359,154, respectively; 2,384,374, respectively; 2,395,010, respectively; 2,537,658, respectively; 2,567,244, respectively; 2,854,385, respectively; 3,052,610, respectively; and 5,662,780 and Eaglesifield et al, "Recovery of Acetic Acid from soluble Aqueous Solutions by Liquid-Liquid Extraction-Part 1,") "The Industrial ChemistVol 29, page 147-.

Several solvent characteristics determine the capital and energy costs of the extractive-distillation process for the extractive recovery of lower acids from wet acid feeds. The solvent used in this extraction process is immiscible with water and meets two criteria:

a) the solvent exhibits some selectivity between the extraction of carboxylic acid and water, i.e., the carboxylic acid/water ratio in the extraction solvent after extraction is significantly greater than in the wet acid feed stream. This factor can be quantified as the water/acid weight ratio in the extract stream as defined in more detail below;

b) the solvent exhibits sufficient affinity and capacity for lower carboxylic acids,

these characteristics can be quantified by an equilibrium partition coefficient determined experimentally as defined in more detail below.

The equilibrium partition coefficient (which may also be used interchangeably with the term "partition coefficient") of component a (lower carboxylic acid) is defined as follows:

。

the partition coefficient is a measure of the relative concentration of the solute to be extracted in the two phases. The value of the acid partition coefficient is directly related to the amount of solvent needed to achieve a given extraction. A low value of the partition coefficient indicates that a high amount of solvent is required and a high value of the partition coefficient indicates that a low amount of solvent is required. Since the acid partition coefficient varies with acid concentration, the minimum amount of solvent required to achieve a given amount of acid extraction also varies. Thus, the control solvent flow requirement for extraction depends on the lowest value of the acid partition coefficient, as the acid concentration changes from a high value of the inlet wet acid feed to a low value of the outlet acid concentration of the effluent raffinate stream.

The control acid distribution coefficient can be defined as:

P_cont= minimum value (P)_raff, P_extr)

Wherein

P_raff= acid partition coefficient at near the desired acid concentration in the raffinate stream (i.e. at low acid concentration); and

P_extr= acid partition coefficient at an acid concentration close to that required in the extract stream, i.e. at high acid concentration.

The most important water-acid selectivity values are those at the extraction end of the extraction cascade. It is defined as:

R_extr = W_extr / A_extr

wherein

W_extr= weight fraction of water in the extraction product stream; and is

A_extr= weight fraction of acid in the extraction product stream.

Controlling the distribution coefficient P_contAnd the extraction water/acid ratio R_extrCan be combined to yield a total extraction factor epsilon, which is a simple measure of the effectiveness of a given solvent in recovering lower acids from a wet acid feed in an extractive-distillation process. The extraction factor epsilon is defined as:

ε = P_cont /R_extr = (P_cont* A_extr) / W_extr

generally, the higher the extraction factor, the lower the capital and energy costs for a given extraction.

Extraction solvents that exhibit reverse behavior are also known. That is, their acid partition coefficients are lowest at the extraction end (high acid concentration) and highest at the raffinate end (low acid concentration) of the cascade. Examples of such solvents include nitriles, phosphate esters, phosphine oxides (U.S. patent nos. 3,816,524 and 4,909,939), and amines (for example)Such as King, "Amine-Based Systems for Carboxylic Acid Recovery: scientific Amines and the property Choice of solvent Extraction and Recovery from Water," CHEMTECH, Vol.5, p.285-291 (1992); and Tamada et al, "Extraction of Carboxylic Acids with Amine extracts. 2. Chemical Interactions and Interpretation of Data"Ind. Eng. Chem. Res.Volume 29, page 1327-1333 (1990)).

This reverse behavior is also observed for the following (partition coefficient is highest at low acid concentrations): phosphonium-and ammonium-phosphinate ionic liquids (Blauser et al, "Extraction of butyl acid with a solvent containing ammonium ionic liquid"Sep. Purif. Technol.,Volume 119, page 102-111 (2013); martak et al, "phosphorus ionic liquids as new, reactive extrectants of lactic acid"Chem. PapersVol.60, pp.395-98 (2006)) and Phosphonium carboxylates (Oliveira et al, "Extraction of L-Lactic, L-Malic, and Succinic Acids Using phosphorus-Based Ionic Liquids"Sep. Purif. Tech.,Volume 85, page 137 and 146 (2012)). In particular, Oliveira et al reported that P was present in most lactic, succinic and malic acid extraction tests_666,14Decanoate does not form a simple two-phase system. The third phase complicates the distribution and recovery of the carboxylic acid.

Poole et al, "Extraction of Organic Compounds with Room Temperature Ionic Liquids"J. Chromatogr. (A)The use of hydrophobic ionic liquids as extraction solvents has been reviewed at 1217, 2268, 2286 (2010). Robertson et al, "Industrial Preparation of phosphorus Ionic Liquids",Green Chem.the development and advantages of Phosphonium Ionic Liquids have been reviewed in volume 5, page 143-152 (2003) and their use for extracting Ethanol from fermentation broths by Neves et al, "Separation of Ethanol-Water Mixtures by Liquid-Liquid Extraction Using Phosphonium-Based Ionic Liquids"Green Chem.Volume 13, pages 1517-1526 (2011) are addressed.

The extraction of lower carboxylic acids using imidazolium and phosphonium ionic liquids has also been reported.For acetic acid, McFarlane et al report bmim-NTf₂、omim-NTf₂、bmim-PF₆、P_666,14-LABS/nonanol, P_444,14-LABS/nonanol and P_666,14-OSO₂Me（“Room Temperature Ionic Liquids for Separating Organics from Produced Waters,” Sep. Sci. & Tech.Vol 40, 1245-. Hashikawa claims P for acetic, propionic, and butyric acids_222,8-NTf₂("Method for Producing Acetic Acid," JP 2014/40389, Daicel, (3/6/2014)). And Matsumoto et al reported bmim-PF₆、hmim-PF₆And omim-PF₆（“Extraction of Organic Acids Using Imidazolium-Based Ionic Liquids and Their Toxicity to Lactobacillus rhamnosus,” Sep. and Purif. Tech.Volume 40, pages 97-101 (2004)).

However, none of these documents uses quaternary phosphonium carboxylates with monofunctional carboxylic acids. Furthermore, the lower carboxylic acid partition was poor in the reports of McFarlane, Hashikawa and Matsumoto. Furthermore, those skilled in the art recognize that the addition of an alcohol to a phosphonium ionic liquid composition for the extraction of lower carboxylic acids is not preferred due to the formation of carboxylic ester derivatives of the alcohol with acid extracts, particularly in downstream distillation or evaporation processes for the purification of lower carboxylic acids. This exclusion is achieved by Judson King, "Acetic Acid Extraction"Handbook of Solvent ExtractionKrieger publication. Co. (1991) was solved.

In particular, Hashikawa only claims the use of ionic liquids with fluorine-containing anions, such as bis (fluorosulfonyl) imide, bis (fluoroalkylsulfonyl) imide, tris (perfluoroalkyl) trifluorophosphate, hexafluorophosphate, tetrafluoroborate and perfluoroalkylsulfonate. These anions add significant cost and toxicity problems for large scale applications. Furthermore, Hashikawa claims ionic liquids having phosphonium salts containing a total of only 10 carbon atoms or more. According to the data presented in the Hashikawa application, triethyl (octyl) phosphonium bis (trifluoromethylsulfonyl) amide shows relatively poor extraction behavior towards acetic acid, with small two-phase region, low acetic acid capacity and very low partition coefficient (between about 0.06 to 0.1).

Despite the poor performance of the ionic liquid systems reported and claimed above, the very low vapor pressure of ionic liquids remains an attractive physical property for the lower carboxylic acid extract phase. Thus, there is a need in the art for an extraction solvent that provides excellent partitioning of lower carboxylic acids from aqueous solutions and enables simple separation of these acids from the solvent via distillation. There is also a need for an extraction solvent with a high extraction factor whereby C can be recovered from wet acid feed in an energy and cost effective manner₁To C₄A carboxylic acid.

These needs and others are addressed by the present invention, which is apparent from the following description and appended claims.

Summary of The Invention

The invention is set forth in the following detailed description and the appended claims.

Briefly, in one aspect, the present invention provides a method for extracting C from water₁To C₄A solvent for the carboxylic acid. The extraction solvent comprises (a) a quaternary phosphonium carboxylate salt and (b) a non-ionic organic solvent, with the proviso that the non-ionic organic solvent is not an extract. The carboxylate has the general formula 1:

wherein

R¹、R²、R³And R⁴Each independently is C₁To C₂₆A hydrocarbon group, provided that R¹、R²、R³And R⁴A total of at least 24 carbon atoms; and is

R⁵Is hydrogen or C₁To C₂₄A non-aromatic hydrocarbon group.

In another aspect, the present invention provides a method for mixing C₁To C₄Composition of carboxylic acid separated from water. The composition comprises:

(a) quaternary phosphonium carboxylates according to the invention;

(b) a non-ionic organic solvent according to the invention;

(c) C₁to C₄A carboxylic acid; and

(d) and (3) water.

In yet another aspect, the present invention provides a method of treating a mammal with C₁To C₄A process for separating carboxylic acid from water. The method comprises the step of enabling the catalyst to contain C₁To C₄A feed mixture of carboxylic acid and water is contacted with an extraction solvent according to the present invention in an effective manner to form (a) a mixture comprising the carboxylic acid salt, the non-ionic organic solvent, and at least a portion of C from the feed mixture₁To C₄An extraction mixture of carboxylic acids and (b) a feed mixture comprising water and less C than the feed mixture₁To C₄A raffinate mixture of carboxylic acids.

In one aspect, the invention relates to a process for separating acetic acid from water. The process comprises contacting a feed mixture comprising acetic acid and water with an extraction solvent comprising a quaternary phosphonium carboxylate salt according to the present invention under conditions effective to form (a) an extraction mixture comprising the carboxylate salt and at least a portion of the acetic acid from the feed mixture and (b) a raffinate mixture comprising water and less acetic acid than the feed mixture.

Brief description of the drawings

The figure shows P at 300 MHz from example 2_666,14-2EH in CDCl₃In (1)¹H NMR spectrum.

Detailed Description

It has been surprisingly found that when certain quaternary phosphonium carboxylates are combined with an aqueous solution of a lower carboxylic acid, the resulting partitioning of the lower acid into the phosphonium carboxylate phase can be quite high, particularly when the concentration of the lower acid is low (e.g., < 5% by weight). The carboxylic acid salts exhibit excellent low acid extraction selectivity over co-extraction with water. Thus, the carboxylate salts have an extraction factor epsilon significantly higher than other types of lower acid extraction solvents and are therefore particularly useful for the recovery of lower acids from wet-process acid streams.

Accordingly, in one aspect, the present invention provides quaternary phosphonium carboxylates useful for separating lower acids from aqueous streams. The carboxylate is depicted by formula 1:

wherein

R⁵Is hydrogen or C₁To C₂₄A non-aromatic hydrocarbon group.

The term "hydrocarbyl" as used herein refers to a group containing hydrogen and carbon atoms and may be straight or branched chain, cyclic or acyclic, and saturated or unsaturated.

R¹、R²、R³And R⁴Each may have the same number of carbon atoms or may have different lengths. In one embodiment, R¹、R²、R³And R⁴Having a total of not more than 54 carbon atoms. In another embodiment, R¹、R²、R³And R⁴Each having at least 6 carbon atoms. In other embodiments, R¹、R²、R³And R⁴Each containing 6 to 24 carbon atoms, 6 to 20 carbon atoms, 6 to 18 carbon atoms, 6 to 14 carbon atoms, or 8 to 14 carbon atoms.

Preferably, R⁵Having a length such that the length of the (C) is equal to that of the (C) phosphonium group [ PR ] as defined above¹R²R³R⁴]In combination, the carboxylate anion renders the salt hydrophobic. In one embodiment, R⁵Is C₃To C₉A non-aromatic hydrocarbon group. In another embodiment, R⁵Is C₃To C₂₀A non-aromatic hydrocarbon group. In other embodiments, R⁵May contain 1 to 20 carbon atoms, 1 to18 carbon atoms, 1 to 16 carbon atoms, 1 to 14 carbon atoms, 1 to 12 carbon atoms, 3 to 20 carbon atoms, 3 to 18 carbon atoms, 3 to 16 carbon atoms, 3 to 14 carbon atoms, or 3 to 12 carbon atoms. R⁵May contain functional groups such as alkoxy, olefinic and halogen functional groups.

By "hydrophobic" is meant that the salt is immiscible in water under typical extraction conditions, e.g., has less than 5 wt% miscibility in water at 20 ℃.

The carboxylate is liquid under typical extraction conditions.

Examples of phosphonium carboxylates having the structure of formula 1 are listed in table 1 below. If the compounds are known, their CAS registry numbers are also listed.

TABLE 1

CAS registry number for some known phosphonium carboxylates

^a Pure & Appl. Chem.Vol 84, page 723 (2012)

^b Green Chem.Vol.7, page 855 (2005)

^cU.S. Pat. No. 5,663,422 (Eastman Chemical; 1997)

NF = not found.

Carboxylate derivatives in table 1 that do not have CAS accession numbers are not previously known and are therefore specifically considered to be within the scope of the present invention.

Mixtures containing more than one quaternary cation and more than one carboxylate anion may also be used to extract lower acids from aqueous solutions and are therefore also considered to be within the scope of the present invention.

In one embodiment, the carboxylate salt comprises a tetraalkylphosphonium salt of formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, linolenic acid, mixed plant-derived acids, or chloroacetic acid.

In another embodiment, the carboxylate salt comprises a trihexyl (tetradecyl) phosphonium salt of formic, acetic, propionic, n-butyric, isobutyric, n-valeric, isovaleric, n-hexanoic, 2-ethylbutyric, heptanoic, n-octanoic, 2-ethylhexanoic, nonanoic, decanoic, dodecanoic, palmitic, stearic, oleic, linolenic, mixed plant-derived acids, or chloroacetic acid.

In yet another embodiment, the carboxylate salt comprises trihexyl (tetradecyl) phosphonium carboxylate. The carboxylic anion may be selected from formate, acetate, propionate, acrylate, butyrate, isobutyrate, methacrylate, hexanoate, 2-ethylbutyrate, octanoate, 2-ethylhexanoate, nonanoate, and decanoate.

Some phosphonium carboxylates having the structure of formula 1 are commercially available, while others can be made by known methods from readily available precursors. See, e.g., Kogelnig et al, "Green Synthesis of New Ammonium Ionic Liquids and the third polar as Extracting Agents"Tetrahedron LettersVol.49, pp.2782-2785 (2008) and Ferguson et al, "A Greener, Halide-Free Approach to Ionic Liquid Synthesis"Pure & Appl. Chem.Vol 84, page 723 and 744 (2012). The former process involves the metathesis of alkali metal carboxylates with quaternary ammonium halides, the latter process uses ion exchange resins, and in our experience (see examples 1 and 2 below) produces ionic liquids with lower amounts of residual halide. One example of a readily available precursor is trihexyl (tetradecyl) phosphonium chloride.

Thus, while synthetic methods of general nature for the preparation of quaternary phosphonium carboxylates are known, relatively small quantities are prepared and their use for the extraction of lower acids from aqueous streams is unknown, except for P for the extraction of lactic, malic and succinic acids reported by Oliveira et al and described herein_666,14-decanoic acid salt. Thus, in one embodiment, the present invention excludes the use of P alone_666,14-decanoic acidSalts for the extraction of aqueous solutions of lactic, malic and succinic acids.

In a second aspect, the present invention provides composition a:

。

composition a represents a unique biphasic mixture comprising a quaternary phosphonium carboxylate according to formula 1, a lower acid and water. Other materials may also be present. Composition a can be used to separate lower acids from water.

As mentioned above, the lower acid means C₁To C₄A carboxylic acid. For example, the carboxylic acid may be a monocarboxylic acid or, an alkoxy carboxylic acid or a halogen containing carboxylic acid. Examples of such acids include formic acid, acetic acid, propionic acid, acrylic acid, n-butyric acid, isobutyric acid, methacrylic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid, trifluoroacetic acid, methoxyacetic acid, and the like. In one embodiment, the C₁To C₄The carboxylic acid is a monocarboxylic acid containing no hydroxyl group.

Producing a diluted aqueous carboxylic acid-containing stream (i.e., comprising less than 1 wt.% to 60 wt.% C in the aqueous mixture)₁To C₄Examples of processes for the production of cellulose esters or terephthalic acid, the production of ketene or higher enones from the high temperature dehydration of carboxylic acids and anhydrides, the hydrolysis of poly (vinyl acetate), the production of fischer-tropsch liquids, the production of oil and gas (producing "produced water"), the ketonization of carboxylic acids to ketones, the oxidation of ethylene to acetaldehyde by the Wacker process, the oxidation of propylene to acrylic acid, the oxidation of oxo-aldehydes to their carboxylic acids, the hydrocarboxylation of formaldehyde with water and carbon monoxide, the oxidation of isobutylene to methacrylic acid, pyroligneous acid, fermentation broths, acetic acid streams (vinegar stream), and the like. By acetic acid stream is meant an aqueous stream comprising acetic acid. In one embodiment, the wet acid feed is derived from the production of cellulose esters.

The wet acid feed may comprise 0.5 to 60 wt% of one or more C₁To C₄A carboxylic acid. More preferably, the wet acid feed comprises 0.5 to 35 wt% C₁To C₄Carboxylic acids. Due to the exceptionally high acid partition coefficient of the inventive carboxylic acid salts even at low acid concentrations, the inventive extraction solvents can be advantageously used for extracting lower acids at concentrations as low as 0.5 wt.% in wet acid feeds.

The terms "feed" and "feed mixture" as used herein are intended to have their commonly understood meaning in the field of liquid-liquid extraction, which is a solution containing the material to be extracted or separated. In the present invention, an example of the "feed" is a mixture composed of one or more of formic acid, acetic acid, propionic acid, acrylic acid, n-butyric acid, isobutyric acid, methacrylic acid, methoxyacetic acid, chloroacetic acid, dichloroacetic acid, trichloroacetic acid and trifluoroacetic acid in water. In the present invention, the terms "feed" and "feed mixture" are synonymous with "aqueous acid stream", "weak acid stream" and "wet acid feed".

The term "extraction solvent" as used herein is intended to be synonymous with the term "extractant" and means a water-immiscible or hydrophobic liquid used in extraction processes to extract materials or solutes from a feed.

The weight ratio of carboxylate to wet acid feed in composition a can vary over a wide range. For example, the ratio may be 0.2 to 10:1, or more preferably 0.3 to 4: 1.

One feature of composition a is that it separates into two phases, an aqueous phase and an organic phase, with the lower acid partitioning between them. The biphasic nature of composition a is desirable to physically separate the lower acid from the aqueous solution. The amount of lower acid partitioned between the phases is limited only by the two-phase nature of the system. The amount of lower acid preferably does not exceed a level at which the biphasic nature of the composition is lost. Other materials may also be present, but only to the extent that the biphasic nature of the system is retained. Complex systems that form more than two phases are not preferred because such systems obscure the effective separation of lower acids (obscure).

Formation of more than two-phase systems, emulsions, or other complex mixtures of quaternary phosphonium carboxylates can be simplified by adding a hydrophobic, non-ionic organic co-solvent to the quaternary phosphonium carboxylate extraction phase.

Therefore, in the third aspect,the present invention provides a process for extracting lower carboxylic acid (C) from water₁ - C₄) The solvent of (1). The extraction solvent comprises a phosphonium carboxylate defined by the above formula 1 and a non-ionic organic (NIO) solvent. The NIO solvent is not an extract (i.e., C to be separated)₁ - C₄Carboxylic acid). Rather, it is separated from and distinct from the lower carboxylic acid to be separated.

The extraction solvent can comprise two or more carboxylic acid salts.

The NIO solvent is preferably selected to impart desirable physical properties to the extraction solvent, such as lower viscosity or higher hydrophobicity, or to provide a composition as described above and described in, for example, U.S. Pat. Nos. 1,861,841; 1,917,391, respectively; 2,028,800, respectively; 3,052,610, respectively; 5,662,780, respectively; 2,076,184, respectively; and 2,204,616 with water to enable drying of the lower carboxylic acid in subsequent purification steps.

Examples of such hydrophobic NIO solvents include ketones, aromatic hydrocarbons, saturated hydrocarbons, ethers, esters, chlorinated hydrocarbons, nitriles, and higher carboxylic acids.

Fatty alcohols, such as nonanol, are not preferred because these may complicate the isolation of the lower acids by forming esters during extraction or subsequent purification. In one embodiment, the NIO solvent excludes fatty alcohols, such as nonanol.

Also care should be taken in selecting a particular compound from any of the above classes of co-solvents that, in combination with a lower acid or water, may form an azeotrope or may be difficult to separate from the lower acid.

Preferred non-ionic organic solvents form a minimum boiling azeotrope with water, but do not form an azeotrope with the lower acid.

In one embodiment, the NIO solvent has 4 to 20 carbon atoms. In another embodiment, the NIO solvent has 4 to 18 carbon atoms. In other embodiments, the NIO solvent has 4 to 16 carbon atoms, 4 to 14 carbon atoms, 4 to 12 carbon atoms, 5 to 20 carbon atoms, 5 to 18 carbon atoms, 5 to 16 carbon atoms, 5 to 14 carbon atoms, or 5 to 12 carbon atoms.

In a particular embodiment, the NIO solvent comprises a higher carboxylic acid. Notably, it has been found that as little as 10 mole percent of higher carboxylic acid in the extraction solvent can significantly increase the partition coefficient of lower acid, particularly at low concentrations in the wet acid stream.

As used herein, "higher carboxylic acid" refers to carboxylic acids having 4 to 20 carbon atoms. In the case where the carboxylic acid to be separated has 4 carbon atoms, the "higher carboxylic acid" contains at least 5 carbon atoms or has a boiling point sufficiently different (e.g. +/-2 ℃) than the lower acid to be separated so that the two can be separated from each other by simple distillation.

In one embodiment, the higher carboxylic acid is selected from the group consisting of n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, linolenic acid, and mixed plant-derived acids.

In another embodiment, the higher carboxylic acid is selected from the group consisting of n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, and 2-ethylhexanoic acid.

Preferred NIO esters are those containing 4 to 6 carbon atoms, such as ethyl acetate, n-propyl formate, isopropyl acetate, isopropyl formate, n-butyl acetate, n-butyl formate, isobutyl acetate, isobutyl formate, n-propyl propionate, and isopropyl propionate.

Preferred NIO ketones are those containing from 5 to 9 carbon atoms, such as 2-pentanone, 3-methyl-2-butanone, 2-hexanone, 2-heptanone, cyclohexanone, 4-methyl-2-pentanone, 2, 4-dimethyl-3-pentanone, 5-methyl-2-hexanone, 4-heptanone, 2-octanone, 5-nonanone, 2, 8-dimethyl-4-heptanone, 3, 5-trimethylcyclohexanone, and isophorone.

Preferred NIO ethers are those containing 4 to 8 carbon atoms, such as diethyl ether, methyl propyl ether, dipropyl ether, di-isopropyl ether, methyl tert-butyl ether, tert-amyl methyl ether, and ethyl butyl ether.

Preferred NIO aromatics include toluene, meta-xylene, para-xylene, and ortho-xylene.

Preferred NIO chlorinated hydrocarbons include dichloromethane, chloroform, dichloroethane, ethylene chloride, carbon tetrachloride and chlorinated derivatives of benzene.

Preferred NIO nitriles include valeronitrile and nitriles boiling above valeronitrile such as capronitrile and benzonitrile.

In one embodiment, the hydrophobic NIO solvent is selected from the group consisting of methyl isobutyl ketone, toluene, isopropyl acetate, and methyl tert-butyl ether.

In another embodiment, the hydrophobic NIO solvent is a fatty carboxylic acid, such as butyric, valeric, caproic, enanthic, caprylic, pelargonic, and C₄-C₉Isomeric forms of carboxylic acids.

The extraction solvent and compositions containing the same according to the present invention may comprise two or more NIO solvents. The use of mixtures of hydrophobic solvents optimally achieves the desired physical properties of the claimed system.

The extraction solvent of the present invention may comprise 0 to 90, 10 to 90, 20 to 90, 30 to 90, 40 to 90, or 50 to 90 weight percent of the NIO solvent. The extraction solvent may also contain 0 to 60, 10 to 60, 20 to 60, 30 to 60, 40 to 60, or 50 to 60 weight percent of a NIO solvent. The balance of the extraction solvent may be constituted by the carboxylate according to the invention.

The NIO solvent may be combined with the carboxylate salt prior to introduction into the extraction vessel. Alternatively, the NIO solvent may be introduced separately into the extraction vessel. In one embodiment, the NIO solvent may be introduced as a second solvent feed on the other side of the extraction cascade than the wet acid feed, such as in a staged extraction mode, where the NIO solvent aids in washing out any carboxylic acid salts from the final raffinate product stream.

The carboxylate salt or mixture of carboxylate salts of the present invention may be combined with one or more NIO solvents in any known manner to form an extraction solvent.

In a fourth aspect, the present invention provides composition B:

。

composition B comprises a carboxylate of formula 1, an NIO solvent, C₁To C₄Carboxylic acid and water. It can be used for mixing lower carboxylic acid with waterIsolating and optionally purifying the lower acid.

Composition B may contain more than one carboxylate, more than one NIO solvent, and/or more than one lower acid. The carboxylate salt, the NIO solvent, and the lower acid can be any of those described herein.

In one embodiment, composition B has only two liquid phases.

Composition B is characterized in that C can be recovered by distillation at atmospheric pressure or lower₁To C₄A carboxylic acid.

The weight ratio of extraction solvent (carboxylate and NIO solvent) to wet acid feed in composition B can vary over a wide range. For example, the ratio may be 0.2 to 10:1, or more preferably 0.3 to 4: 1.

In a fifth aspect, the present invention provides a method of treating a mammal with C₁To C₄A process for separating carboxylic acid from water. The method comprises the step of enabling the catalyst to contain C₁To C₄A feed mixture of a carboxylic acid and water is contacted with an extraction solvent comprising a quaternary phosphonium carboxylate salt according to the present invention and a nonionic organic solvent according to the present invention in an amount effective to form (a) a composition comprising the carboxylate salt, the nonionic organic solvent, and at least a portion of C from the feed mixture₁To C₄An extraction mixture of carboxylic acids and (b) a feed mixture comprising water and less C than the feed mixture₁To C₄A step of contacting under conditions of a raffinate mixture of carboxylic acids.

The extraction of the feed mixture (i.e., the contacting step) may be carried out by any means known in the art for intimately contacting two immiscible liquid phases and separating the resulting phases after the extraction procedure. For example, the extraction can be performed using columns, centrifuges, mixer-settlers, and a wide variety of devices. Some representative examples of extractors include unstirred columns (e.g., sprays, baffled trays and packings, perforated plates), agitated columns (e.g., pulsed, rotating agitated and reciprocating plates), mixer-settlers (e.g., pump-settlers, static mixer-settlers, and agitated mixer-settlers), centrifugal extractors (e.g., those produced by Robatel, Luwesta, deLaval, Dorr Oliver, Bird, CINC, and Podbielniak), and other miscellaneous extractors (e.g., emulsion phase contactors, electrically enhanced extractors, and membrane extractors). A description of these devices can be found in "Handbook of Solvent Extraction," Krieger Publishing Company, Malabar, FL, pp.275-501 (1991). The various types of extractors can be used alone or in any combination.

The extraction may be carried out in one or more stages. The number of extraction stages can be selected based on many factors, such as capital cost, achieving high extraction efficiency, ease of operation, stability of feed and extraction solvent, and extraction conditions. The extraction can also be carried out in batch or continuous mode of operation. In continuous mode, the extraction can be performed in co-current, counter-current, or as a staged extraction (where multiple solvents and/or multiple solvent feed points are used to help facilitate separation). The extraction process can also be carried out in a plurality of separation zones which can be connected in series or in parallel.

The extraction may be carried out at an extraction solvent to feed mixture weight ratio of, for example, 0.2 to 10:1, or more preferably 0.3 to 4: 1.

The extraction can generally be carried out at a temperature of from 10 to 140 ℃. For example, the extraction may be carried out at a temperature of 30 to 110 ℃. The desired temperature range may be further limited by the boiling point of the extractant component or water. Typically, it is undesirable to run the extraction under conditions where the extractant boils. In one embodiment, the extractor can be operated to establish a temperature gradient across the extractor to improve mass transfer kinetics or decantation rate.

If the temperature selected for the extraction is greater than the normal boiling point of any lower acid to be extracted, any component making up the extraction solvent, or water; the extractor can be operated at a pressure sufficient to suppress boiling of any of the above components. The extraction may generally be carried out at a pressure of from 1 bar to 10 bar, or from 1 bar to 5 bar.

The separation process of the present invention may further comprise separating the extract from the raffinate and recovering C from the extract by distillation at atmospheric pressure or lower₁To C₄And (3) carboxylic acid. Any known method of separating the liquid extract from the raffinate may be used. Likewise, any known distillation technique may be used to recover the solvent from the extractionA lower acid.

In one embodiment, the present invention provides a process for separating acetic acid from water. The process comprises contacting a feed mixture comprising acetic acid and water with an extraction solvent comprising a quaternary phosphonium carboxylate salt according to the present invention under conditions effective to form (a) an extraction mixture comprising the carboxylate salt and at least a portion of the acetic acid from the feed mixture and (b) a raffinate mixture comprising water and less acetic acid than the feed mixture.

This acetic acid separation process can be carried out using any of the modes described above.

The extraction solvent used in this process may further comprise one or more NIO solvents according to the invention.

The acetic acid separation process may further comprise the steps of separating the extraction mixture from the raffinate mixture and recovering acetic acid from the extraction mixture by distillation at atmospheric pressure or lower.

These additional steps may also be performed as described above.

The present invention includes and expressly contemplates any and all combinations of embodiments, features and/or ranges disclosed herein. That is, the invention may be defined by any combination of the embodiments, features and/or ranges set forth herein.

The indefinite articles "a" and "an" as used herein mean one or more than one unless the context clearly dictates otherwise. Similarly, the singular forms of nouns include their plural forms and vice versa unless the context clearly dictates otherwise.

As used herein, the term "and/or," when used in reference to a listing of two or more items, means that any one of the listed items can be used by itself or any combination of two or more of the listed items can be used. For example, if a composition is described as containing components A, B and/or C, the composition may contain only a; only contains B; only contains C; contains A and B; contains A and C; contains B and C; or A, B and C.

Notwithstanding any attempt to achieve precision, the numerical values and ranges set forth herein should be considered as approximations (even if not limited by the term "about"). These values and ranges may vary from their stated values depending on the desired properties sought to be obtained by the present invention, as well as the variations resulting from the standard deviations found in the measurement techniques. Moreover, the ranges described herein are intended and are expressly contemplated to include all sub-ranges and values within the specified range. For example, a range of 50 to 100 is intended to describe and include all values within the range, including sub-ranges such as 60 to 90 and 70 to 80.

The contents of all documents, including patent and non-patent documents, cited herein are hereby incorporated by reference in their entirety. In the event that any incorporated subject matter contradicts any disclosure herein, the disclosure herein should take precedence over the incorporated content.

The invention may be further illustrated by the following examples of preferred embodiments thereof, although it will be understood that these examples are included merely for purposes of illustration and are not intended to limit the scope of the invention.

Examples

Abbreviations used in the following examples are summarized in table 2.

TABLE 2

Abbreviations

Compound (I)	Abbreviations
		Acetic acid	HOAc
Propionic acid	HOPr
		N-butyric acid	n-HOBu
Isobutyric acid	i-HOBu
		2, 2-dimethylbutyric acid	2,2-DMB acid
2-Ethylbutyric acid	2EB acid
		2-ethyl hexanoic acid	2EH acid
Nitrile butadiene	PrCN
		Methyl tert-butyl ether	MTBE
Tert-amyl methyl ether	TAME
		4-heptanone	DPK
Ethyl acetate	EtOAc
		Acetic acid isopropyl ester	i-PrOAc
N-propyl acetate	n-PrOAc
		Acetic acid n-butyl ester	n-BuOAc
Acetic acid isobutyl ester	i-BuOAc
		2-pentanone	MPK
4-methyl-2-pentanone	MIBK
		5-methyl-2-hexanones	MIAK
2-heptanone	MAK
		Phosphoric acid tributyl ester	TBP
Triethyl phosphate	TEHP
		Cyanex 923 mixture of trialkyl phosphine oxides with octyl and hexyl groups	C923
1-ethyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide	emim-NTf₂
		1-butyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide	bmim-NTf₂
1-butyl-3-methylimidazolium acetate	bmim-OAc
		1-butyl-3-methylimidazolium bis (trifluoro)Ethylsulfonyl) amide	bmim-BETI
1-butyl-3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate	bmim-FAP
		1-hexyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide	hmim-NTf₂
1-octyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide	omim-NTf₂
		1-octyl-3-methylimidazolium bis (trifluoroethylsulfonyl) amide	omim-BETI
1-decyl-3-methylimidazolium bis (trifluoromethylsulfonyl) amide	C₁₀mim-NTf₂
		1-butyl-2, 3-dimethylimidazolium bis (trifluoromethylsulfonyl) amide	C₄mmim-NTf₂
1- (2-methoxyethyl) -3-methylimidazolium tris (pentafluoroethyl) trifluorophosphate	MeOEtmim-FAP
		1- (8-hydroxyoctyl) -3-methylimidazolium bis (trifluoromethylsulfonyl) amide	HOC₈mim-NTf₂
3-methylimidazolium bis (trifluoromethylsulfonyl) amide	C₈-H₄F₁₃mim-NTf₂
		Dimethylaminoethyl-dimethylethylammonium bis (trifluoromethyl) sulfonyl amide	iPr₂N(CH₂)₂mim-NTf₂
1-butylpyridinium bis (trifluoromethylsulfonyl) amide	bpyr-NTf₂
		1- (2-methoxyethyl) -pyridinium tris (pentafluoroethyl) trifluorophosphate	MeOEtpyr-FAP
1- (4-cyanobutyl) -3-methylimidazolium bis (trifluoromethylsulfonyl) amide	(4-CN)bmim-NTf₂
		Trimethyl (butyl) ammonium bis (trifluoromethylsulfonyl) amide	N₁₁₁₄-NTf₂
Trimethyl (octyl) ammonium bis (trifluoromethylsulfonyl) amide	N₁₁₁₈-NTf₂
		1- (2-diisopropylaminoethyl) dimethylethylammonium bis (trifluoromethyl) sulfonylamide	iPr₂N(CH₂)₂N₂₁₁-NTf₂
Dimethylaminoethyl-dimethylethylammonium bis (trifluoromethyl) sulfonyl amide	Me₂N(CH₂)₂N₂₁₁-NTf₂
		Choline bis (trifluoromethylsulfonyl) amide	choline-NTf₂
1-butyl-1-methylpyrrolidinium bis (trifluoromethylsulfonyl) amide	C4mpyrr-NTf₂
		N-trimethylbetaine bis (trifluoromethylsulfonyl) amide	C₁Hbet-NTf₂
Triethyl (octyl) phosphonium bis (trifluoromethylsulfonyl) amide	P₂₂₂₈-NTf₂
		Trioctyl (methyl) phosphonium bis (trifluoromethylsulfonyl) amide	P₈₈₈₁-NTf₂
1- (2-diisopropylaminoethyl) trioctylphosphonium bis (trifluoromethyl) sulphonyl amide	iPr₂N(CH₂)₂P₈₈₈-NTf₂
		Trihexyl (tetradecyl) phosphonium chloride	P_666,14-Cl
Trihexyl (tetradecyl) phosphonium hydroxide	P_666,14-OH
		Trihexylphosphonium bis (trifluoromethylsulfonyl) amide	P_666,14-NTf₂
Trihexyl (tetradecyl) phosphonium tris (pentafluoroethyl) trifluorophosphate	P_666,14-FAP
		Trihexyl (tetradecyl) phosphonium formate	P_666,14-formate
Trihexyl (tetradecyl) phosphonium acetate	P_666,14-OAc
		Trihexyl (tetradecyl) phosphonium isobutyrate	P_666,14-isobutyrate
Trihexyl (tetradecyl) phosphonium hexanoate	P_666,14-hexanoate
		Trihexyl (tetradecyl) phosphonium 2-ethylbutanoate	P_666,14-2EB
Trihexyl (tetradecyl) phosphonium 2, 2-dimethylbutyrate	P_666,14-2,2-DMB
		Trihexyl (tetradecyl) phosphonium octanoates	P_666,14-octanoate
Trihexyl (tetradecyl) phosphonium 2-ethylhexanoate	P_666,14-2EH
		Trihexyl (tetradecyl) phosphonium dodecanoate	P_666,14-dodecanoate
Trihexyl (tetradecyl) phosphonium succinate	P_666,14-succinate

Example 1

_666,14Synthesis of P-OH

Will P_666,14-Cl (81.70 g, 157.32 mmol) was dissolved in methanol (19.78 g, 617.35 mmol) and the solution was settled down for further ion exchange reaction. Using ion exchange resin (170 cm)³Amberlite IRN-78) packed column and the resin washed with methanol. Then the P is added_666,14The Cl solution was slowly added to the column, and the flow rate was controlled at 1 drop/2 sec. Thereafter, methanol (80 mL, 1977.03 mmol) was slowly added to the column to add all P_666,14OH was washed out into a 500 mL single-necked round bottom flask. All P contained in the column was collected_666,14After the solution of-OH, 5 drops of the solution were mixed with 3 drops of HNO₃And 3 drops of AgNO₃Mixed to test whether all halogen ions have been exchanged. This procedure is repeated as necessary.

In solution of P_666,14Concentration of-OH¹H NMR analysis, and P in methanol_666,14The weight% of-OH is determined by the relative integral of acidic proton to the hydrocarbon chain of methyl versus phosphonium salt of methanol.

Example 2

_666,14Synthesis of P-2EH

P in methanol determined in example 1_666,14Calculated weight fraction of-OH (P)_666,14Weight fraction of OH = 0.3032), the neutralization P is calculated as follows_666,14-acids required for OH:

MW = 144.21 for 2-EH Acid;

P_666,14MW = 500.86 for OH;

weight of desired 2-EH Acid = { [ (weight of hydroxide MeOH solution) ((P))_666,14Weight% of-OH] / (P_666,14MW of-OH) } { (MW of 2-EH Acid) = { [ (252.36 g) } [0.3032/(500.86 g/mol)]} * (144.12 g/mol) = 22.017 g。

2-Ethylhexanoic acid (22.04 g, 152.93 mmol) was added to the P_666,14-OH solution, then the solution was stirred for 6 hours. Then rotate onThe solution was dried in a rotary evaporator at 40 ℃ for 6 hours. Further drying was carried out in a high vacuum drying system for 6 hours. The formed carboxylate salt is then ready for liquid-liquid extraction (LLE) experiments and further characterization, such as moisture content measurement, differential scanning calorimetry, thermogravimetric analysis, and elemental analysis.

The figure shows P at 300 MHz_666,14-2EH in CDCl₃In (1)¹H NMR spectrum.

Example 3

Acetic acid extraction using representative NIO solvents

The tie line data at high (typically about 16-20 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 1-5 wt% HOAc in the organic phase) were measured for each solvent at the temperatures given in table 3.

Approximately equal masses of water and solvent were added to the glass vials. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by gas chromatography for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 3.

TABLE 3

Acetic acid extraction factor of non-ionic organic solvents

Solvent(s)	T (℃)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
						EtOAc	25	0.99	1.5	0.98	1.01
n-BuOAc	40	0.41	1.6	0.52	0.79
						nPrOAc	40	0.51	2.2	0.70	0.73
iPrOAc	40	0.54	1.8	0.65	0.83
						PrCN	20	2.85	17.0	0.7	4.07
2EH Acid	40	0.32	1.3	0.29	1.10
						MTBE	40	0.7	2.0	0.5	1.40
TAME	40	0.42	1.5	0.34	1.24
						2-hexanones^a	35	0.91	3.9	0.97	0.93
MIBK	35	0.65	1.6	0.53	1.23
						MAK	40	0.49	1.7	0.41	1.20
MIAK	40	0.46	1.7	0.34	1.35
						DPK	40	0.32	1.3	0.31	1.03
Isophorone	40	1.1	1.2	0.67	1.64

^aData is taken fromJ. Chem. Eng. Data, 46, 2001, 1450-56。

Although PrCN has a relatively high extraction factor, it has the same boiling point as acetic acid, forms an azeotrope with acetic acid, and is therefore very difficult to separate from acetic acid.

Example 4

Acetic acid extraction using phosphate ester solvents

The tie-line data at high (typically about 15-20 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 1-2 wt% HOAc in the organic phase) were measured for each solvent (either the pure phosphate or a mixture of phosphate and NIO solvent) at the temperatures given in table 4.

Approximately equal masses of water and solvent were added to the glass vials. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by gas chromatography for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 4.

TABLE 4

Acetic acid extraction of phosphate ester-containing compositions at 40 deg.C

Solvent(s)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					Phosphoric acid tributyl ester	0.78	18.1	0.39	2.00
25 wt% TBP, 75 wt% MTBE	0.94	19.7	0.52	1.81
					25 wt% TBP, 75 wt% iPrOAc	0.80	18.1	0.61	1.31
Triethyl phosphate	0.33	16.2	0.12	2.75
					25 wt.% TEHP, 75 wt.% MTBE	0.71	16.9	0.30	2.37
25 wt.% TEHP, 75 wt.% iPrOAc	0.62	15.8	0.39	1.59

Such as those manufactured by Wardell and King ("Solvent Equilibria for Extraction of Carboxylic Acids from Water"J. Chem. and Eng. DataVol 23, number 2, pp 144-148 (1978)) expected that the extraction factor of phosphate solvents was slightly improved compared to those of NIO solvents.

Example 5

Acetic acid extraction using Cyanex 923

The tie-line data at high (typically about 15-20 wt% HOAc in the organic phase) and low acetic acid concentration (typically about 1-2 wt% HOAc in the organic phase) were measured for each solvent (commercially available Cyanex 923 or mixtures of Cyanex 923 and non-ionic organic solvents) at the temperatures given in table 5.

Approximately equal masses of water and solvent were added to the glass vials. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by gas chromatography for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. KnotThe results are listed in table 5.

TABLE 5

Acetic acid extraction factor at 40 ℃ for Cyanex-containing compositions

Solvent(s)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					Cyanex 923	0.94	19.0	0.26	3.62
75 wt% MTBE/25 wt% C923	0.89	20.0	0.36	2.47
					75 wt% iPrOAc/25 wt% C923	0.77	20.0	0.43	1.79

Example 6

Acetic acid extraction using hydrophobic liquid salts

The tie line data at high (typically about 7-25 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) were measured for each solvent at the temperatures specified in table 6.

Some solvents exhibit very low acid partition coefficients, and the two-phase region does not extend much above about 7 wt% acetic acid. Equilibrium data for each compound was measured in the following manner.

3 g of solvent were pipetted into a jacketed glass tankTo this was added 3 grams of an aqueous mixture of acetic acid (prepared to generate high or low acid concentration data). A stir bar was introduced into the vial and the contents were sealed with a plastic cap and a layer of sealing film tape. The cell is maintained at the desired temperature by means of a constant temperature fluid circulated through the jacket of the cell. The mixture was stirred vigorously for 1.5 hours and then allowed to separate into a clear phase without stirring while maintaining the specified temperature. After 6 hours settling time, the phases were sampled and analyzed by NMR for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 6.

TABLE 6

Extraction of acetic acid in a series of hydrophobic solvents at 20 deg.C

Solvent(s)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					emim-NTf₂	0.30	7.1	0.85	0.35
bmim-NTf₂	0.21	1.4	0.69	0.31
					bmim-NTf₂ ^b	0.24	5.4	0.79	0.30
bmim-FAP	0.00	1.5	0.17	0.00
					bmim-FAP^b	0.06	1.7	0.33	0.18
bmim-BETI	0.06	0.6	0.39	0.15
					hmim-NTf₂	0.19	4.6	0.56	0.34
omim-NTf₂	0.18	0.9	0.47	0.38
					omim-NTf₂ ^a	0.12	11.8	0.68	0.17
omim-BETI	0.05	0.5	0.50	0.11
					C₁₀mim-NTf₂	0.13	3.6	0.39	0.34
C₄mmim-NTf₂	0.13	1.1	0.59	0.22
					iPr₂N(CH₂)₂mim-NTf₂	0.18	4.5	0.88	0.20
MeOEtmim-FAP	0.04	0.3	0.23	0.15
					4CNbmim-NTf₂	0.65	11.0	0.82	0.79
HOC₈mim-NTf₂	0.54	7.6	0.98	0.55
					(C₆F₁₃)-(C₂H₄)mim-NTf₂	0.08	0.7	0.60	0.13
C₄mpyrr-NTf₂	0.33	9.5	0.45	0.74
					bpyr-NTf₂	0.22	5.1	0.69	0.31
MeOEtpyr-FAP	0.06	0.2	0.23	0.26
					N₁₁₁₄-NTf₂	0.13	1.9	0.84	0.16
N₁₁₁₈-NTf₂	0.06	1.2	0.47	0.14
					Me₂N(CH₂)₂N₂₁₁-NTf₂	0.53	9.5	2.00	0.26
iPr₂N(CH₂)₂N₂₁₁-NTf₂	0.14	4.0	0.77	0.19
					choline-NTf₂	0.82	14.0	1.64	0.50
C₁Hbet-NTf₂	0.76	12.7	1.48	0.51
					P₂₂₂₈-NTf₂ ^b	0.10	2.8	0.33	0.30
P₄₄₄₄-2EH	0.52	7.3	1.452	0.36
					P₈₈₈₁-NTf₂	0.05	0.8	0.43	0.13
iPr₂N(CH₂)₂P₈₈₈-NTf₂	0.21	5.4	0.74	0.28
					P_666,14-Cl	0.38	8.5	0.63	0.60
P_666,14-NTf₂	0.06	1.8	0.88	0.07
					P_666,14-FAP	0.02	0.1	0.23	0.10

^aEquilibrating at 75 ℃ instead of 20 ℃

^bData were taken from Hashikawa, JP appl. Kokai 2014/40389.

Example 7

Acetic acid extraction using tetraalkyl phosphonium carboxylates

The tie line data at high (typically about 9-21 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) were measured at 20 ℃ for each of the solvents listed in table 7.

Approximately equal masses of water and solvent were added to the glass vials. All extraction solvents contained essentially 100 mole% of the carboxylic acid salt. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by NMR for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 7.

TABLE 7

Extraction of different phosphonium carboxylates with acetic acid at 20 deg.C

Solvent(s)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					P_666,14-formate salt	2.47	19.7	0.28	8.73
P_666,14-acetate salt	4.98	9.1	1.08	4.59
					P_666,14-hexanoic acid salt	3.32	20.3	0.25	13.48
P_666,14-2EB	2.15	21.6	0.24	8.91
					P_666,14-2,2-DMB	2.41	20.3	0.29	8.32
P_666,14-octanoic acid salts	3.17	19.9	0.24	12.99
					P_666,14-2EH	3.24	20.4	0.21	15.21
P_666,14Dodecyl sulfate salt	2.62	20.2	0.23	11.17
					P_666,14-succinic acid salt	4.72	11.9	0.58	8.07

Example 8

_666,14 ₁ ₄C to C carboxylic acid extraction using P-2EH

The bond line data at high (typically about 16-25 wt% lower acid in the organic phase) and low acid concentrations (typically about 0.2 to 5 wt% in the organic phase) were measured at 20 ℃ for each of the acids listed in table 8.

Approximately equal masses of water and solvent were added to the glass vials. All extraction solvents contained essentially 100 mole% of the carboxylic acid salt. Acid is added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Upon addition of the lower acid, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by NMR for water and lower acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acid weight ratio R at high acid concentrations_extr. The results are shown in Table 8.

TABLE 8

Multiple carboxylic acid extraction of P666,14-2EH

Hyaluronic acid	P_cont	At P_contCarboxylic acid of (b)% by weight	R_extr	Extraction factor (epsilon)
					Formic acid	1.35	16.5	0.19	7.03
Acetic acid	3.24	20.4	0.21	15.21
					Propionic acid	7.64	25.1	0.16	47.28
N-butyric acid	4.64	22.0	0.17	27.05
					Acrylic acid	4.77	20.9	0.16	28.49

Example 9

_666,14Acetic acid extraction using P-2EH and/or NIO co-solvents

The tie line data at high (typically about 20-25 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) are measured at 20 ℃ for each of the solvents listed in table 9.

Approximately equal masses of water and extraction solvent containing varying amounts of carboxylate and NIO solvent were added to the glass vials. N-hexanoic acid and 2-ethylhexanoic acid (2-EH acid) were tested as NIO solvents. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. Taking each phaseSamples were analyzed by NMR for water and acetic acid (wt%). These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 9.

The results of the extractions with 2-EH acid alone and n-hexanoic acid alone are included in Table 9 for comparison.

TABLE 9

Effect of NIO solvent identity and concentration on acetic acid extraction

Carboxylate solvents	NIO solvent	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
						Is free of	100 mol% 2-EH acid^a	0.32	0.32	0.29	1.10
Is free of	100 mol% of n-hexanoic acid	0.56	1.8	1.07	0.53
						P_666,14-2EH	Is free of	3.24	20.4	0.21	15.21
P_666,14-2EH	10 mol% 2-EH acid	2.19	21.7	0.21	10.40
						P_666,14-2EH	30 mol% 2-EH acid	1.80	19.7	0.22	8.18
P_666,14-2EH	50 mol% 2-EH acid	0.86	23.9	0.22	3.87
						P_666,14-2EH	80 mol% 2-EH acid	0.53	25.8	0.30	1.79
P_666,14-2EH	90 mol% 2-EH acid	0.48	25.0	0.46	1.05
						P_666,14-2EH	10 mol% of n-hexanoic acid	2.26	20.9	0.22	10.03
P_666,14-2EH	20 mol% of n-hexanoic acid	1.97	20.5	0.22	8.73
						P_666,14-2EH	30 mol% of n-hexanoic acid	2.00	19.6	0.24	8.31
P_666,14-2EH	50 mol% of n-hexanoic acid	1.15	20.5	0.27	4.21

^aEquilibration at 40 ℃.

Example 10

_666,14Acetic acid extraction using P-hexanoic acid salt and/or n-hexanoic acid

The tie line data at high (typically about 20 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) were measured at 20 ℃ for each of the solvents listed in table 10.

Approximately equal masses of water and extraction solvent containing varying amounts of carboxylate and NIO solvent were added to the glass vials. N-hexanoic acid was tested as the NIO solvent. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by NMR for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 10.

The results of the extraction with n-hexanoic acid alone are included in table 10 for comparison.

Watch 10

Effect of n-hexanoic acid on acetic acid extraction of P666, 14-hexanoic acid salt

Of n-hexanoic acidAmount (mol%)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					Is free of	3.32	20.3	0.25	13.48
30	2.97	19.3	0.26	11.36
					50	1.80	19.6	0.27	6.63
70	1.15	15.4	0.43	2.69
					90	0.65	14.7	0.86	0.76
95	0.68	14.3	1.19	0.57
					100	0.56	1.8	1.07	0.53

Example 11

_666,14Acetic Acid extraction using P-2EB and/or 2-EB Acid

The tie line data at high (typically about 14-20 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) are measured at 20 ℃ for each of the solvents listed in table 11.

Approximately equal masses of water and extraction solvent containing varying amounts of carboxylate and NIO solvent were added to the glass vials. 2-Ethylbutyric acid was tested as a NIO solvent. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by NMR for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 11.

TABLE 11

Effect of 2-EB Acid on acetic Acid extraction of P666,14-2EB

Amount of 2EB Acid (mol%)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					Is free of	2.15	21.6	0.24	8.91
10	4.75	20.7	0.24	19.80
					30	2.76	22.6	0.26	10.58
50	2.05	19.9	0.29	7.05
					70	1.59	14.4	0.50	3.18
80	1.01	14.4	0.63	1.61
					90	1.01	14.2	0.85	1.19
95	0.82	14.2	1.10	0.74

Example 12

_666,14Acetic acid extraction using P-isobutyrate and i-HOBu

The tie line data at high (typically about 20 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) were measured at 20 ℃ for each of the solvents listed in table 12.

Approximately equal masses of water and extraction solvent containing varying amounts of carboxylate and NIO solvent were added to the glass vials. Isobutyric acid was tested as the NIO solvent. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by NMR for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 12 in (c).

TABLE 12

Effect of isobutyric acid on acetic acid extraction of P666, 14-isobutyrate

Amount of isobutyric acid (mol%)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					10	3.19	19.3	0.273	11.69
30	2.08	20.6	0.255	8.16
					50	1.67	18.8	0.275	6.08

Example 13

_666,14Acetic acid extraction using P-n-octanoate and/or n-octanoic acid

The tie line data at high (typically about 20-25 wt% HOAc in the organic phase) and low acetic acid concentrations (typically about 0.2 to 5 wt% HOAc in the organic phase) are measured at 20 ℃ for each of the solvents listed in table 13.

Approximately equal masses of water and extraction solvent containing varying amounts of carboxylate and NIO solvent were added to the glass vials. N-octanoic acid was tested as the NIO solvent. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once added toAcetic acid, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by NMR for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data was also used to calculate the water/acetic acid weight ratio R at high acid concentrations_extr. The results are shown in Table 13.

Watch 13

Effect of caprylic acid on acetic acid extraction of P666, 14-caprylate

Amount of octanoic acid (% by mol)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					Is free of	3.17	19.9	0.24	12.99
50	1.03	25.7	0.21	4.76

Example 14

Effect of temperature on extraction Using NIO solvent

The tie line data was measured at 22 and 40 ℃ for each of the solvents listed in table 14.

Approximately equal masses of water and solvent were added to the glass vials. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously, followed by maintaining the specificationsThe temperature was simultaneously allowed to separate into a clear phase. The phases were sampled and analyzed by gas chromatography for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. The results are shown in Table 14.

TABLE 14

Effect of temperature on acetic acid partitioning in NIO solvent

Solvent(s)	T (℃)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
						MTBE	22	0.86	2.0	0.46	1.88
MTBE	40	0.70	2.0	0.50	1.40
						MIBK	22	0.67	3.9	1.14	0.59
MIBK	40	0.75	8.4	0.73	1.02
						i-PrOAc	22	0.57	1.7	0.56	1.02
i-PrOAc	40	0.54	1.8	0.65	0.83

As seen from table 14, the partition coefficient and extraction factor respond differently to temperature changes in different NIO solvents.

Example 15

_666,14Effect of temperature on acetic acid extraction Using P-carboxylates

The tie line data was measured at 20 and 75 ℃ for each of the solvents listed in table 15.

Approximately equal masses of water and solvent were added to the glass vials. Acetic acid was added to the solvent-water mixture in an amount sufficient to generate high or low acid concentration data. Once acetic acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by gas chromatography for water and acetic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. The results are shown in Table 15.

Watch 15

Effect of temperature on acetic acid extraction of P666, 14-Carboxylic acid salts

Carboxylate solvents	NIO solvent	T (℃)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
							P_666,14-2EH	Is free of	20	3.24	20.4	0.21	15.21
P_666,14-2EH	Is free of	75	1.86	20.2	0.24	7.59
							P_666,14-hexanoic acid salt	Is free of	20	3.32	20.3	0.25	13.48
P_666,14-hexanoic acid salt	Is free of	75	1.89	21.0	0.12	16.15
							P_666,14-hexanoic acid salt	10 mol% hexanoic acid	75	2.14	21.5	0.24	8.91
P_666,14-2EB	Is free of	20	2.15	21.6	0.24	8.91
							P_666,14-2EB	Is free of	75	1.87	20.9	0.27	6.94
P_666,14-2EB	10 mol% 2-EB acid	75	2.24	20.0	0.26	8.63

As with the NIO solvents (see table 14), both the partition coefficient and the extraction factor increased and decreased with respect to temperature in different phosphonium carboxylate solvents (see table 15). Notably, in some cases, the extraction factor increases with increasing temperature.

Procedures of examples 16 to 19

Three NIO solvents (MIBK, MTBE, and n-butyl acetate) and a carboxylate solvent P were used_666,14-2EH measurement of the bond line data for the extraction of lower carboxylic acids (formic, propionic, n-butyric and acrylic acids) from water.

The bond line data at high (typically about 10-25 wt% carboxylic acid in the organic phase) and low acid concentrations (typically about 1 to 5 wt% acid in the organic phase) were measured for each solvent at 40 ℃.

Approximately equal masses of water and solvent were added to the glass vials. The desired amount of carboxylic acid is added to the solvent-water mixture in an amount sufficient to generate data for high or low acid concentrations. Once the acid was added, the mixture was stirred vigorously and then allowed to separate into a clear phase while maintaining the specified temperature. The phases were sampled and analyzed by gas chromatography for water and carboxylic acid wt%. These data are used to calculate the distribution coefficient and control the distribution coefficient P_contIs considered to be the smaller of the partition coefficients at high and low acid concentrations. This data is also used to calculate the water/carboxylic acid weight ratio R at high acid concentrations_extr。

Example 16

_666,14Formic acid extraction with NIO solvent compared to P-2EHGet

This example presents the use of NIO solvents (MTBE, MIBK and n-butyl acetate) and P according to the extraction procedure described above_666,14-2 extraction factor of EH extraction of formic acid. The results are shown in Table 16.

TABLE 16

Partitioning of the NIO solvent with formic acid in P666,14-2EH (40 ℃ C.)

Solvent(s)	P_cont	At P_contHOAc (wt%) of	R_extr	Extraction factor (epsilon)
					MTBE	0.7	16.8	0.69	1.0
MIBK	0.6	14.3	0.74	0.8
					BuOAc	0.4	10.0	0.58	0.6
P_666,14-2EH	1.35	16.5	0.191	7.0

Example 17

_666,14Propionic acid extraction with NIO solvent compared to P-2EH

This example presents the use of NIO solvents (MTBE, MIBK and acetic acid) according to the extraction procedure described aboveN-butyl ester) and P_666,14-2 extraction factor for EH extraction of propionic acid. The results are shown in Table 17.

TABLE 17

Partition of the NIO solvent with propionic acid in P666,14-2EH (40 ℃ C.)

Solvent(s)	P_cont	At P_contPropionic acid (wt%)	R_extr	Extraction factor (epsilon)
					MTBE	3.2	20.2	0.30	10.7
MIBK	2.6	18.8	0.46	5.5
					BuOAc	2.0	17.7	0.30	6.50
P_666,14-2EH	7.64	25.1	0.16	47.3

Example 18

_666,14N-butyric acid extraction with NIO solvent compared to P-2EH

This example presents the use of NIO solvents (MTBE, MIBK and n-butyl acetate) and P according to the extraction procedure described above_666,14-2 extraction factor for EH extraction of n-butyric acid. The results are shown in Table 18.

Watch 18

Partition of the NIO solvent with n-butyric acid in P666,14-2EH (40 ℃ C.)

Solvent(s)	P_cont	At P_contButyric acid (wt%)	R_extr	Extraction factor (epsilon)
					MTBE	9.9	25.2	0.20	48.5
MIBK	8.4	23.0	0.31	27.3
					BuOAc	6.8	22.1	0.22	30.9
P_666,14-2EH	4.6	22.0	0.17	27.0

Example 19

_666,14Acrylic acid extraction with NIO solvent compared to P-2EH

This example presents the use of NIO solvents (MTBE, MIBK and n-butyl acetate) and P according to the extraction procedure described above_666,14-2EH extraction factor for acrylic acid. The results are shown in Table 19.

Watch 19

NIO solvent and acrylic partitioning in P666,14-2EH (40 ℃ C.)

Solvent(s)	P_cont	At P_contAcrylic acid (wt%) of	R_extr	Extraction factor (epsilon)
					MTBE	3.6	24.2	0.31	11.8
MIBK	2.7	21.6	1.40	6.8
					BuOAc	2.1	20.6	0.30	6.9
P_666,14-2EH	4.8	20.9	0.17	28.5

The invention has been described in detail with particular reference to preferred embodiments thereof, but it will be understood that variations and modifications can be effected within the spirit and scope of the invention.

Claims

1. For mixing C₁To C₄A composition for separating carboxylic acid from water, the composition comprising:

(a) a quaternary phosphonium carboxylate;

(b) a hydrophobic non-ionic organic solvent selected from ketones, aromatic hydrocarbons, saturated hydrocarbons, ethers, esters, chlorinated hydrocarbons, nitriles and higher carboxylic acids, wherein the higher carboxylic acids refer to carboxylic acids having 4 to 20 carbon atoms;

(c) C₁to C₄A carboxylic acid; and

(d) the amount of water is controlled by the amount of water,

wherein the hydrophobic non-ionic organic solvent is not an extract, and

wherein the quaternary phosphonium carboxylate has the general formula 1:

wherein

R⁵Is hydrogen or C₁To C₂₄Non-aromatic hydrocarbon radicals, in which R⁵Optionally containing alkoxy functionality or halogen functionality.

2. The composition of claim 1, wherein the quaternary phosphonium carboxylate salt comprises a tetraalkylphosphonium salt of formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, linolenic acid, mixed plant-derived acids, or chloroacetic acid.

3. The composition of claim 1, wherein the quaternary phosphonium carboxylate salt comprises a trihexyl (tetradecyl) phosphonium salt of formic, acetic, propionic, n-butyric, isobutyric, n-valeric, isovaleric, n-hexanoic, 2-ethylbutyric, heptanoic, n-octanoic, 2-ethylhexanoic, nonanoic, decanoic, dodecanoic, palmitic, stearic, oleic, linolenic, mixed plant-derived or chloroacetic acids.

4. The composition according to claim 1, wherein the quaternary phosphonium carboxylate salt comprises trihexyl (tetradecyl) phosphonium carboxylate.

5. A composition according to claim 1 comprising at least two quaternary phosphonium carboxylates.

6. The composition according to claim 1, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of higher carboxylic acids, ethers, esters, ketones, aromatic hydrocarbons, chlorinated hydrocarbons and nitriles.

7. The composition according to claim 6, wherein the hydrophobic non-ionic organic solvent comprises a higher carboxylic acid.

8. The composition of claim 7, wherein the higher carboxylic acid is selected from the group consisting of n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, linolenic acid, and mixed plant-derived acids.

9. The composition of claim 8 wherein the higher carboxylic acid is selected from the group consisting of n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, and 2-ethylhexanoic acid.

10. The composition according to claim 1, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of esters containing 4 to 6 carbon atoms, ketones containing 5 to 9 carbon atoms and ethers containing 4 to 8 carbon atoms.

11. The composition according to claim 1, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of ethyl acetate, n-propyl formate, isopropyl acetate, isopropyl formate, n-butyl acetate, n-butyl formate, isobutyl acetate, isobutyl formate, n-propyl propionate, isopropyl propionate, 2-pentanone, 3-pentanone, methyl isobutyl ketone, 3-methyl-2-butanone, 2-hexanone, 2-heptanone, cyclohexanone, 4-methyl-2-pentanone, 2, 4-dimethyl-3-pentanone, 5-methyl-2-hexanone, 4-heptanone, 2-octanone, 5-nonanone, 2, 8-dimethyl-4-heptanone, 3, 5-trimethylcyclohexanone, isophorone, Diethyl ether, methyl propyl ether, dipropyl ether, diisopropyl ether, methyl tert-butyl ether, tert-amyl methyl ether, ethyl butyl ether, toluene, m-xylene, p-xylene and o-xylene.

12. The composition according to claim 11, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of methyl isobutyl ketone, toluene, isopropyl acetate and methyl tert-butyl ether.

13. A composition according to claim 1, comprising at least two hydrophobic non-ionic organic solvents.

14. A composition according to claim 1 comprising 10 to 90% by weight of the quaternary phosphonium carboxylate salt and 10 to 90% by weight of the hydrophobic non-ionic organic solvent.

15. A composition according to claim 1 comprising 50 to 90% by weight of the quaternary phosphonium carboxylate salt and 10 to 50% by weight of the hydrophobic non-ionic organic solvent.

16. A kind of bag C₁To C₄A process for separating carboxylic acid from water, the process comprising:

make it contain C₁To C₄A feed mixture of a carboxylic acid and water is contacted with an extraction solvent comprising a quaternary phosphonium carboxylate salt and a hydrophobic nonionic organic solvent in an amount effective to form (a) a composition comprising the quaternary phosphonium carboxylate salt, the hydrophobic nonionic organic solvent, and at least a portion of C from the feed mixture₁To C₄An extraction mixture of carboxylic acids and (b) a feed mixture comprising water and less C than the feed mixture₁To C₄A raffinate mixture of carboxylic acids,

wherein the hydrophobic non-ionic organic solvent is not an extract, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of ketones, aromatic hydrocarbons, saturated hydrocarbons, ethers, esters, chlorinated hydrocarbons, nitriles, and higher carboxylic acids, and wherein the higher carboxylic acid refers to a carboxylic acid having 4 to 20 carbon atoms; and is

Wherein the quaternary phosphonium carboxylate has the general formula 1:

wherein

R⁵Is C₁To C₂₀Non-aromatic hydrocarbon radicals, in which R⁵Optionally containing alkoxy functionality or halogen functionality.

17. The method of claim 16, wherein the quaternary phosphonium carboxylate salt comprises a tetraalkylphosphonium salt of formic acid, acetic acid, propionic acid, n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, palmitic acid, stearic acid, oleic acid, linolenic acid, mixed plant-derived acids, or chloroacetic acid.

18. The method according to claim 16, wherein the quaternary phosphonium carboxylate salt comprises trihexyl (tetradecyl) phosphonium carboxylate.

19. The process according to claim 16, wherein the extraction solvent comprises at least two quaternary phosphonium carboxylates.

20. The process according to claim 16, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of higher carboxylic acids, ethers, esters, ketones, aromatic hydrocarbons, chlorinated hydrocarbons and nitriles.

21. The process according to claim 20, wherein the higher carboxylic acid is selected from the group consisting of n-butyric acid, isobutyric acid, n-valeric acid, isovaleric acid, n-hexanoic acid, 2-ethylbutyric acid, heptanoic acid, n-octanoic acid, 2-ethylhexanoic acid, nonanoic acid, decanoic acid, dodecanoic acid, stearic acid, oleic acid, linolenic acid, and mixed plant-derived acids.

22. The process according to claim 20, wherein the hydrophobic non-ionic organic solvent is selected from the group consisting of ethyl acetate, n-propyl formate, isopropyl acetate, isopropyl formate, n-butyl acetate, n-butyl formate, isobutyl acetate, isobutyl formate, n-propyl propionate, isopropyl propionate, 2-pentanone, 3-pentanone, methyl isobutyl ketone, 3-methyl-2-butanone, 2-hexanone, 2-heptanone, cyclohexanone, 4-methyl-2-pentanone, 2, 4-dimethyl-3-pentanone, 5-methyl-2-hexanone, 4-heptanone, 2-octanone, 5-nonanone, 2, 8-dimethyl-4-heptanone, 3, 5-trimethylcyclohexanone, isophorone, Diethyl ether, methyl propyl ether, dipropyl ether, diisopropyl ether, methyl tert-butyl ether, tert-amyl methyl ether, ethyl butyl ether, toluene, m-xylene, p-xylene and o-xylene.

23. The method of claim 16, wherein the extraction solvent comprises at least two hydrophobic, nonionic organic solvents.

24. The process according to claim 16, wherein the extraction solvent comprises 10 to 90 wt% of the quaternary phosphonium carboxylate salt and 10 to 90 wt% of the hydrophobic non-ionic organic solvent.

25. The method of claim 16, wherein said C₁To C₄The carboxylic acid comprises acetic acid.

26. The process according to claim 16, wherein the feed mixture comprises at least two C' s₁To C₄A carboxylic acid.

27. The process according to claim 16, wherein the feed mixture comprises from 0.5 to 60 wt% of C₁To C₄A carboxylic acid.

28. The process according to claim 16, wherein said feed mixture is derived from the production of cellulose esters.

29. The process according to claim 16, wherein the weight ratio of the extraction solvent to the feed mixture is from 0.2 to 10: 1.

30. The method of claim 16, further comprising:

separating the extraction mixture from the raffinate mixture; and

recovering C from the extraction mixture by distillation at atmospheric pressure or lower₁To C₄A carboxylic acid.